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    <title>Document</title>
    <script>
        // 1、我们需要一个临时变量帮我们
        // 2、把apple1里面的苹果给我们的临时变量temp
        // 3、把apple2里面的苹果给apple1
        // 4、把临时变量里面的苹果给apple2
        var temp; //声明一个临时变量为空
        var apple1 = '青苹果';
        var apple2 = '红苹果';
        temp = apple1; //把右边里的值给左边
        apple1 = apple2;
        apple2 = temp;
        console.log(apple1);
        console.log(apple2);
    </script>
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